Infosecdad

The stock exhaust on my ‘01 Impreza 2.5 RS was 1.75” ID. That matches up to what you measured.

Interesting, that's a different scenario. What's the count pattern for #1 and #4 when in boost? The "threshold" is a little squishy based on what I've read. Many differing opinions on it. I prefer <5, but ok with occasional <15. I've managed to throw a CEL for a 15 on #1 before, not sure if it was because it came back a few times or just was consistent for a long enough time. Before replacing intake gaskets, I could get into the 60-80 range and it would run like it was on 3 cylinders, but no CEL. Go figure

The signup page says 25yr membership, so I'm pretty sure it isn't expiring unless something changed.

Today’s errands were very promising. Still just minimal single digit misfires on #1 Idle is definitely smoother. LV says fuel trims are better (closer to zero) I’ll have a good test when I have to go to Atlanta on Monday.

From my research, cleaning may work for a bit, but most everyone seems to end up replacing them not terribly long after. I decided to replace mine at 195k, I would like to think I will get to do it again at 400k miles :-P

That's good info, thanks. I'll use that for future gasket replacements.

Very cool, I love how much I can fit in my wagon. Are you missing a tail light?

I *might* have the old style. Kinda hard to tell after 14yrs and 195k miles. The new gaskets are definitely taller, softer, and have larger nubs for holding it in place. Whether or not the ones I pulled out where like that 14yrs ago, I have no idea. Could definitely tell a difference between the two when installed. With the old ones, the intake would touch the TGVs. With the new ones, it floated just off the surface. So I'm hoping these are good for another 200k...

So, as typical for me, once I have the parts, I can't sit on them. I replaced the 4 orange o-rings between the intake and TGVs last night, wrapped up about 1am. I pulled the TMIC, front two coolant lines to the coolant tank, the TB hose, and half the intake box. That got me just about an inch per side of clearance. I used a big screwdriver to prop up the intake one side at a time. I managed to get just enough room to get my pinky or index fingers under to push in the new gaskets. The 90 degree pick was the ticket. Without that I would have never completed this job with so little space. All in all, it took me about 2.5hrs with an hour because of one stupid bolt... It's done, I don't think I want to do it again, my hands are really beat up. There is almost no room to work if you don't take the intake all the way off. The HKS metal inlet made for a challenge to access the two bolts under it. Thankfully the coupler at the turbo allows for just a little play so I could shift it up or over just enough. One of these is not like the other... As I was removing the 6 bolts per side on the intake, the left rear (closest to the turbo) sheared off. The bolt had frozen to the TGV. I got everything else done, then drilled out what was remaining, retapped, and somehow found a bolt the same size/thread as the others. One drive today to get donuts for the kids (excuse to test it), and the results are promising. Idle is a bit smoother and I only had a few 1s or 2s on the 1/3 cylinders for the trip. That's a small sample, but compared to the last 3 wks, it's promising. Will keep a close eye on it, have errands to run over the weekend and have to drive to ATL on Monday.

For me, I've checked those, three times. I've replaced a couple of the harness plugs because they had fallen apart. I've twisted the pins slightly for contact and ziptied them because I could. If they are the reason at this point, I'm going to have to just solder them directly to the coil

I would expect a large, more systemic issue is causing mine because of how many cylinders are impacted. That's why I was looking that things that would actually bridge the two banks, since I'm not sure how likely it is to have valve clearance issues on 3 of 4 cylinders crop up all at the same time. I'm still trying to mull over what things in the over all system could be impacting, also understanding that many times for stuff like this it may not be a single source, but rather multiple factors chained together. The other tricky part is a "misfire" can be due to many different things as we've learned over the course of this thread and others.

I'm open to suggestions. I've been working on an Infamous base tune. I have BtSSM up on my nexus full time because I like to see the data. I see the P301-304 in EcuFlash, they are flagged as "enabled" Is it just setting the value to "disabled" or is it something else?

You know what they say about misery and company... No, that's a depressing counter Yeah, I would be pretty salty as well. My steps are likely: 1. Replace orange o-rings between intake and tgvs 2. Check valve clearance Anticipated: 3. Cry because it's due to valve clearance 4. Debate whether to try to do just the valve adjustment or go all in 5. Realize that "all in" is a full reseal and probably a clutch 6. Drive the car for a while to build up the feeling of joy when driving to help me get through all this work... I have to travel for work next week, we'll see if I try the o-rings over the weekend or not. Depends what the four kids and wife have in mind...

Oh, it's reoccurring... Just gets to count to 6 before the revs reset the counter... Yeah, no #4 on this trip... Though I've had CEL for everything but #2 at this point.

Dang it, why do you have to be so logical.... On the trip to pick up the gaskets, misfire counts on #3 and #1 were very small. Peaked at 6. 90%+ stopped at a traffic light... Now have the orange o-rings, the gaskets for TGV to head, and valve cover/spark plug tube gaskets.

Awesome, thank you. You are right, it’s the first result for that search, it’s actually 1 of only 2 results. :-D I did buckets back on my old ‘99 outback, but that was when everything was out of the engine bay. I’ll have to think about that, if I’m going that deep, I’m at 80k on my current timing belt... Hopefully the dealer has my gaskets in soon and I can get that part taken care of.

You and me both :-P Do you have a thread about adjusting the valves? That’s my next research project along with replacing the o-rings.

I may try to do the orange rings first since the whole thing doesn't have to come out. For counts it depends on the day, sometimes in the single digits or 10s and repeats, sometimes into the 20s or 30s, or even 60s once. It's wildly inconsistent. Sometimes it just never happens and on occasion I get enough to trigger the CEL. My favorite is when it's enough to trigger the CEL, then goes away so it drives smoothly with the flashing cruise light...

Bringing this back after I read every single post in it... I have a misfire on #3, #1, and #4... sometimes... It usually happens when colder, but not 100% of the time. It is starting when I first start the car, sometimes. I can feel it missing, it's like chugging on 3 cylinders. No misfires listed until it warms up enough to start counting, but I can feel it. Once fully warm, it usually stops. Until then, it'll misfire on 3, 1, & 2 at idle when stopped primarily, but occasionally while moving. Bumping the throttle will typically reset it or stop the counter. When it clears, you can definitely feel it; if moving it goes from shudder to roaring smooth. It started on #3 when it finally got colder here in Chatt, then also on #1, #2 was added to the mix last week. The injectors were cleaned and flow tested <1yr ago, so I've ruled them out so far. I swapped #3 and #1 coils, and the main misfire moved to #1. Aha I said, it's a coil and replaced it; misfires just laughed at me and kept coming despite the replacement. I replaced the plugs (OEM) because they were at 55k miles, it didn't make a diff. I've considered valve adjustment, but since it is on 3 of 4 cylinders I've held off. - Fuel Trims are nice and all vacuum lines have been replaced - When not misfiring, she is so smooth and ready to go - Front 02 is <1yr old - MAF is <1yr old - STi FPR - Coils have 0-25k miles on them - Injectors where cleaned and flow tested passing in flying colors last year - FRP vacuum reference was moved - Fuel pump is AEM replaced a couple years ago - New OCVs I'm considering the intake O-rings and gasket on the other side of the TGVs since I'm at 195k miles, but not really keen on pulling the intake manifold unless I really have to.

If you look back a page or two, I should have a picture as well from the driver’s seat.

Very nice, you got the updated design, that looks like a perfect fit.

HKC-Speed or eBay

Mine is a magnetic mount and sitting on my roof right in front of the rear gate.

Sounds like it. https://www.scangauge.com/products/scangauge-ii/